DLL1 and Infertility: Specifically, Van Sinderen et al. (46) showed soluble delta-like ligand 1 (DLL1) was increased in the uterine lavage of infertile patients, which was associated with increased intracellular “a disintegrin and metalloprotease” protease-17 (ADAM17) expression in endometrial tissue and reduced epithelial adhesiveness of RL95 cells.